Malicious Office (OLE) / .XLS — malware analysis report

Static analysis result for SHA-256 86eaffb28ff03932…

MALICIOUS

Office (OLE) / .XLS

95.0 KB First seen: 2022-07-05
MD5: 6910de28760b7e9f289a1d1086b0cf0c SHA-1: 10be93b5eddc786b253990cc56bdec1a4f95e1b5 SHA-256: 86eaffb28ff03932fcbd61d14266cdbd796f16a8cbed75b2d42cc460f2ee8f29
80 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The file is an Excel document with a significant amount of slack space, indicating potential obfuscation or hidden content. The presence of Excel 4.0 (XLM) macros, specifically an 'auto_open' macro, strongly suggests an attempt to automatically execute malicious code upon opening. The document body is heavily corrupted and unreadable, preventing further analysis of its intended lure.

Heuristics 3

  • OLE document has large unaccounted-for region high OLE_SLACK_ANOMALY
    OLE file is 97,295 bytes but its declared streams total only 0 bytes — 97,295 bytes (100%) live in unallocated sector slack. This is the canonical hiding place for pre-macro-era Office exploit payloads (XOR-encoded shellcode reached via a parser pointer-corruption bug in the document structure).
  • Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPEN
    Workbook contains an Excel 4.0 macro sheet sub-stream — XLM is rarely seen in modern legitimate workbooks and was a major Office malware vector during 2020-2022.
  • CFB header with no readable streams medium OLE_PARSE_EMPTY_STREAMS
    The file begins with a valid OLE2/CFB header but exposes no directory streams. A non-empty compound document with an unreadable directory is anomalous — it is seen with truncated/corrupt files and, more importantly, with content deliberately shifted off byte boundaries to defeat parsers while the host application still recovers the object.